Which forks do I have?

[OzJavelin]

I have a GS750 8-valve which has an Australia compliance plate dated 1/1978, which I'm assuming means it was actually built in 1977. I've been wanting to buy a Tarozzi fork brace for it and there seem to be two models:
* 24-0037 = 1977
* 24-0040 = 1978
My assumption was that 24-0037 was both '77 and '78 and 24-0040 was '79 up for 8Vs. Looks at the specs from Tarozzi my fork tubes are 35mm with 58mm mounting diameter which are the same as the '79 unit (not 37mm and 57x50mm for '78).
I'm confused. Do I have some "crossover" model, export model, or juct the wrong forks?

[tkent02]

I'm pretty sure the only difference in pre 1980 750 forks is that some of them are made for dual front brakes, there may be a slight difference in the fork seals..

[OzJavelin]

I've been wanting to buy a Tarozzi fork brace for it and there seem to be two models:
* 24-0037 = 1977
* 24-0040 = 1978

Correction (typo):
* 24-0037 = 1977
* 24-0040 = 1979